Christopher Mores, SM, ScD, associate professor in the Department of Pathobiological Sciences, has received an award from the National Institutes of Health (NIH), National Institute of General Medical Sciences (NIGMS) to join the group Models of Infectious Disease Agent Study (MIDAS). This research network uses computational modeling techniques to better understand the spread of contagious diseases and to calculate the potential impact of public health measures.

Dr. Mores is the principal investigator for a project entitled, “Predicting vector-borne virus transmission and emergence potential.” The award will provide more than $3 million over the next five years for Dr. Mores and his consortium of researchers from LSU, Tulane University, and the University of New Mexico, to investigate and predict the transmission and potential for emergence of various arthropod-borne viruses (or arboviruses), particularly dengue.

Dengue is an arbovirus transmitted by mosquitoes, primarily Aedes aegypti. It is one of the few arboviruses that almost exclusively affects humans, causing over 50 million cases annually. Dengue historically has been a tropical disease, but international travel has facilitated the expansion of its range into other parts of the world.

Dengue can cause high fever, chills, headache, pain behind the eyes, rash, mild bleeding of the nose or gums, and excruciating joint and muscle pain (hence the common name of “break-bone fever”). Since dengue is caused by a virus, there is no specific treatment. While this traditional form of disease is very painful and convalescence is slow, most patients recover fully.

However, more serious manifestations called dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS) appeared in the mid-20th century. The symptoms of DHF and DSS are the same as the typical form of the disease at first, but as the initial fever declines, the patient starts vomiting and develops abdominal pain and difficulty in breathing. Skin hemorrhages, bleeding nose and gums, and internal bleeding may also occur, and capillaries become “leaky,” allowing plasma, the fluid component of blood, to seep from the vessels into the body cavity. This may lead to circulatory system failure, shock, and death if not recognized early and treated properly. Incidence of these severe forms of dengue is increasing. There are four serotypes, or strains, of the dengue virus, but infection with one serotype does not confer immunity to the others, and some data indicate that infection with a second serotype puts individuals at higher risk for these severe disease forms.

“Dengue is spreading into the southern and southwestern United States,” said Dr. Mores. “Most of the dengue cases detected in the U.S. are imported, but the number of locally acquired cases is increasing. The entire Gulf coast is at potential risk from dengue,” Dr. Mores said. “Our borders are constantly being challenged by this introduced virus—it is being brought in by travelers and becoming established in local mosquito populations. Since 2009, we’ve seen local transmission of dengue in the U.S. when people vacationing in Key West became infected after being bitten by local mosquitoes. Furthermore, in 2010, Puerto Rico witnessed an extensive outbreak with over 10,000 cases reported. The vector density needed to achieve transmission is very low, so it doesn’t take many infected mosquitoes to trigger an outbreak.”

The aim of Dr. Mores’s project is to use mathematical modeling to more accurately forecast the transmission of dengue and other viral diseases, particularly in the U.S. Of particular interest are the specific factors that affect transmission in the vector and human populations separately, and then how these factors combine to affect overall transmission of the virus.

“A problem with predicting the potential for emergence and spread of these viral diseases,” said Dr. Mores, “has been that often the data from field and clinical research don’t get into the hands of the people doing the mathematical modeling. We’ve seen that the researchers making the applied discoveries and the modelers working on the theoretical end sometimes don’t communicate well with each other because they don’t speak the same technical language. And when people doing the modeling don’t have all the data they need, they must make assumptions, and sometimes those assumptions aren’t as accurate as they could be.”

The work planned by Dr. Mores’s consortium is expected to provide improved forecasting of outbreaks of dengue and other arboviruses, predicting them before they begin or detecting them while still in the early stages, and to help the public health community get an accurate estimate of the scope of a burgeoning outbreak to better guide responses.

“What we intend to do is look at the whole system of vector-borne viral diseases to help us get a better estimate of the transmission and emergence potential of these viruses through incorporation of clinical, field, and experimental data into theoretical models,” said Dr. Mores. “We will also be looking at other mosquito-borne viruses such as chikungunya and Rift Valley fever, which also have the potential to expand into the southern U.S. via infected travelers, animals, and vectors, and become entrenched in local mosquito populations.”

“Dr. Mores has assembled a diverse and talented team to study the spread of insect-borne diseases, like dengue fever, which threaten to emerge in the U.S.,” said James Anderson, Ph.D., who helps manage the MIDAS program at the National Institutes of Health. “The team will first concentrate on establishing the factors that drive the spread of dengue and assessing the impact of community-based and international intervention strategies. They will then seek to apply their findings to modeling the spread of other insect-borne diseases, an approach that will nicely complement the other projects in the MIDAS consortium.”

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